Magnet hand tools, such as ferrous object pickup tool and magnetic sweepers, are widely used for commercial and other applications. One popular form of a magnetic hand tool has a magnetic head which is generally disk shaped, made with speaker magnets in the form of generally circular rings. Ferrous steel plates are placed on opposite sides of the disk to create the north an south poles of the magnet. The magnetic flux is concentrated in the two plates. The central hole in the ring-shaped is relatively large, e.g. approximately one third the size of the outer diameter of the magnet. The circular ring shaped magnet is held between upper and lower steel plates, by which the magnet is polarized across the width of the ring between the opposite planar sides. The plates are configured to match the outer perimeter of the ring magnet, so that the magnet is completely sandwiched between the plates. To assemble the tool, this requires that the radial edges of the upper and lower plates be nearly perfectly aligned with the outer perimeter of the magnet and permanently held in this position. In the prior art, the alignment is done by hand. A rivet or other fastener is passed through the plates and through hole in the magnet to keep the assembly tightly stacked together. Because the hole in the magnet is larger than the diameter of the fastener, an adhesive, applied between the plates and the magnet, is relied upon to keep the magnet in lateral alignment with the plates. The use of adhesive is very disadvantageous in the assembly of the tool, because the adhesive must be applied prior to fitting the plates to the magnet. The strong attraction of the plates to the magnet causes the plates to forcefully snap against the magnet, squeezing excess adhesive out of the plate/magnet interface and creating a mess on the exterior perimeter of the assembly. It is not practical to slide the plates into position over the magnet because the plates will effectively scape any adhesive off. Also, once the adhesive degrades, whether from age or exposure to solvents, there is no back-up means in place to retain lateral alignment of the magnet with the plates.
Although magnetic tools of this type can be assembled prior to magnetizing the magnet in a magnetizer, this approach is disadvantageous for the reason that the assembled tools must then be individually magnetized, or a very large magnetizer is required which will accept multiple tools. Also, the steel plates assembled close against the magnet block the magnetic field of the magnetizer from reaching the magnet. With the steel plates attached to the magnet, saturation of the sandwiched magnet within a magnetizer is reduced, especially when multiple magnet/plate assemblies are placed together in a magnetizer. As shown in FIG. 4A, in a stack or array of magnets, with each magnet being sandwiched between steel plates, the magnetic field of a magnetizer is blocked from saturating the magnets, particularly those in the middle of the array between the north and south poles of the magnetizer. Thus magnetizing the bare magnet ceramic prior to assembly is preferred.